Acute kidney injury represents a significant problem in clinical medicine. Five percent of hospitalized patients and up to 30 percent of patients in intensive care units will develop acute kidney injury (“AKI”). In AKI, serum creatinine levels rise slowly and it may take 2-3 days before kidney injury becomes apparent, in general indicated by an increase in creatinine of at least 0.3 mg/dl or an increase of more than 50 percent from baseline (Devarajan, Expert Opinion Med Diagn 2008, 2: 387-398).
The pathogenesis of postoperative AKI appears multifactorial, and its association with increased morbidity and long term mortality is well established (Brown et al Ann Thorac Surg 2008, 86: 4-11).
Coronary bypass surgery is preferentially carried out in patients in whom percutaneous coronary intervention is not possible due to the localization or extent of coronary atherosclerosis. This intervention is associated with a significant risk of AKI, this risk has been described to range between 10 and 20%, and wherein 1 to 5 percent of these individuals require dialysis (Mehta, Circulation 2006: 114 2208-16).
AKI may be prevented in patients who are known to be at increased risk by maintaining a careful fluid balance during surgery and, avoiding other precipitating factors of AKI, such as discontinuation of ACE inhibitors, NSAIDs and other drugs known to cause kidney injury before surgery, and the careful use of diuretics, specifically loop diuretics. Details are summarized in Brit J. of Hospital Medicine, 2008, 69, 450-454 (for details see Tables 2 and 3).
It is important to recognize early evidence of acute kidney injury in particular in low risk population which is frequently subject to early discharge. Although many cases are reversible if diagnosed and treated early, the overall survival rate remains about 50 percent because many patients with AKI have significant underlying disorders, e.g. sepsis, respiratory failure. Frequently death is caused by these disorders, rather than by the renal failure itself. In about 10 percent of the cases dialysis or transplant is required, either as an immediate treatment or as renal function slowly deteriorates. AKI can be fully reversible if treated appropriately and in time. As mentioned above, renal function may also deteriorate to chronic renal failure. Treatment may include immediate treatment of pulmonary edema and hyperkalemia; dialysis; adjustment of drug regimen, restriction of water, Na, and K intake, phosphate binders and Na polystyrene sulfonate.